A French court on Thursday told Twitter to identify people who had posted anti-Semitic and racist entries on the social network.

Twitter is not sure it will comply. And the case is yet another dust-up in the struggle over speech on the Internet, and which countries’ laws prevail.

The court order came in a lawsuit brought by French groups who said the Twitter postings, which were made under pseudonyms, broke French law against racist speech. Twitter has said that under its own rules, it does not divulge the identity of users except in response to a valid court order in the United States, where its data is stored. Twitter has already removed some of the content at issue from its site in France, in keeping with company policy to remove posts in countries where they violate the law.

On Thursday, Twitter said in a brief statement that it would review its legal options after the French ruling; officials at the company’s San Francisco headquarters did not respond to numerous requests for comment.

It remains unclear whether French prosecutors will press their case across the Atlantic and force Twitter’s hand in an American court under a time-consuming process detailed in a so-called mutual legal assistance treaty.

The case revolves around the broad question of which country’s laws have jurisdiction over content on the Internet. This question has become increasingly complicated as vast piles of information are stored in sprawling data centers, known as the cloud, that are accessible over the Internet anywhere, anytime.

“It is a big deal because it shows the conflict between laws in France and laws in the U.S., and how difficult it can be for companies doing business around the world,” said Françoise Gilbert, a French lawyer who represents Silicon Valley companies in courts on both continents.

In this case, the jurisdictional issue has an additional wrinkle because Twitter does not have an office in France and does not face the prosecution of its employees here, a problem that other Web companies, like Facebook and Google, have faced elsewhere. Twitter is popular in France, nonetheless. It is available to anyone with an Internet connection and sells ads on its site here. This could embolden French authorities to try to apply its laws to the service.

With 200 million users, most of them outside the United States, Twitter has confronted these conundrums over hate speech and free expression before, especially in Europe.